# 判断是否存在
scores = {'zs': 100, 'ls': 98, 'ww': 45}

print('zs' in scores)
print('zl' not in scores)

# 删除指定键值对
del scores['zs']
print(scores)

# 清空字典
scores.clear()
print(scores)

scores['zl'] = 98
print(scores)

scores['zl'] = 100
print(scores)
